Fix apparmor_parser not found error in desktop postinst script (#9728)

Add a runtime guard in the postinst so apparmor_parser is only called
  when available. Previously, packages built on Ubuntu 24+ would fail to
  install on headless servers or systems without AppArmor tools. A warning
  is printed when the profile load is skipped to aid debugging.

pkg/debian/build.sh

@@ -86,7 +86,11 @@ EOF
 #!/bin/sh
 
 echo "Load apparmor pgAdmin profile..."
-apparmor_parser -r /etc/apparmor.d/pgadmin4
+if command -v apparmor_parser >/dev/null 2>&1; then
+  apparmor_parser -r /etc/apparmor.d/pgadmin4
+else
+  echo "Warning: apparmor_parser not found, skipping profile load. pgAdmin desktop may not work on Ubuntu 24+ with userns restrictions."
+fi
 EOF
   chmod 755 "${DESKTOPROOT}/DEBIAN/postinst"
 fi